Drilling method and an assembly for performing the method

ABSTRACT

The invention provides a drilling method for drilling a bore-hole in ground or soil, with a percussion drilling device operated directly in the bore-hole and with a rotary percussion drilling device operated from the surface of the ground or soil, both devices being received in a common support member and adapted to be simultaneously operated, and a drilling assembly for preforming this method. In order to avoid a damage of the percussion drilling device, the drilling impact forces and vibrations directed to the rotary percussion drilling device are registered, elastically dampened and absorbed prior to having an effect on the percussion drilling device.

FIELD OF THE INVENTION

The present invention refers to a drilling method for drilling abore-hole in ground or soil, with a percussion drilling device operateddirectly in the bore-hole and with a rotary percussion drilling deviceoperated from the surface of the ground or soil, both devices beingreceived in a common support member and adapted to be simultaneouslyoperated; and a drilling assembly for drilling a bore-hole in ground orsoil, comprising a first percussion drilling device operated directly inthe bore-hole, a second rotary percussion drilling device operated fromthe surface of the ground or soil, both said first and second devicesbeing received in a common support member and adapted to besimultaneously operated.

PRIOR ART

A number of different drilling methods and drilling assemblies are knownin the art for managing different drilling tasks with the considerationof different ground or soil compositions which can vary not only betweenone place and another one, but also from the surface of the ground orsoil to the bottom thereof. Particularly, the hydraulically operatedpercussion drilling devices have proven to be effective, which comprisea percussion tube provided with a percussion drilling crown at their oneend and which are driven by means of a hydraulically operated rotaryimpact drilling mechanism. The percussion tube is screwed into a holderwhich is connected to the rotary impact drilling mechanism whereby itmust be ensured that the screwed connection of the percussion tube isnot loosened during the drilling operation under the influence of therotating and impact forces.

The document DE-AS (German Published Patent Application) Nr. 1,298,066discloses an assembly for the superimposed drilling of holes in rockyground covered with lose soil or scree materials. The assembly comprisesan outer drilling tube with an outer drilling crown and an innerdrilling tube with an inner drilling crown. The outer drilling tube andthe inner drilling tube are connected to a common flush head memberwhich is to be coupled to a drilling and/or percussion device. Thereby,close to the inner drilling crown, there is provided a deep hole hammerdevice which forms part of the inner drilling tube.

Further, the document DE-AS (German Published Patent Application) Nr.1,909,931 discloses an assembly for the superimposed drilling of holes .The assembly comprises an inner drilling tube with an inner drillingcrown and an outer drilling tube with an annular drilling crown which isconnected to a percussion drilling device. There is provided a separaterotary percussion drilling drive comprising rotary driving means andpercussion driving means for both the inner and outer drilling tubes,both of the drive means being controllable independently from eachother.

Furthermore, the pneumatically or hydraulically operated percussionhammer devices, the so-called down-the-hole hammers, have also proven tobe very effective. These devices also comprise a tube in which, at theone end thereof, there is provided the hammer device with a chisel.Thereby, in these devices, the tube has not to transmit impact forces ortorque forces; thus, it is screwed in a holder by means of a simplenormal right-handed thread. An impact and rotary effect is createddirectly, pneumatically or hydraulically, in the down-the-hole hammerdevice and transformed to the chisel which is an integral part of thehammer.

OBJECTS OF THE INVENTION

In many cases, under corresponding geological conditions, it would bedesirable to simultaneously work with a pneumatic down-the-hole hammersituated in the bore-hole and with a percussion drilling machine whichis hydraulically or pneumatically operated from the surface. However,this is not possible if the same installation is used, i.e. by providinga down-the-hole hammer in the interior of the impact tube of thepercussion drilling device, because the impact forces directed to thepercussion drill of the percussion drilling device also affect thedown-the-hole hammer and possibly damage the same; furthermore, underadverse conditions, the vibrations could effect a loosening of the tubethread.

Thus, it is an object of the invention to provide a drilling method andan assembly which allow to simultaneously operate with a down-the-holehammer and a percussion drilling device by using the same installation.Thereby, neither the down-the-hole hammer should be damaged by theimpact forces directed to the percussion drilling device nor the tubereceiving the down-the-hole hammer should be loosened or removed fromits threaded joint.

SUMMARY OF THE INVENTION

To meet these and other objects, the invention provides a drillingmethod for drilling a bore-hole in ground or soil, with a percussiondrilling device operated directly in the bore-hole and with a rotarypercussion drilling device operated from the surface of the ground orsoil, both devices being received in a common support member and adaptedto be simultaneously operated. The drilling impact forces and vibrationsdirected to the rotary percussion drilling device are registered,elastically dampened and absorbed prior to having an effect on saidpercussion drilling device.

The invention also provides a drilling assembly for drilling a bore-holein ground or soil, comprising a first percussion drilling deviceoperated directly in the bore-hole and a second rotary percussiondrilling device operated from the surface of the ground or soil. Bothsaid first and second devices are received in a common support memberand are adapted to be simultaneously operated. The assembly comprises adrilling hammer with a chisel member connected to an inner tube of thedrilling hammer and an outer tube with a drilling crown surrounding theinner tube. The inner tube supporting the drilling crown is connected,via a shock absorber element, to the common supporting member which iscoupled to the rotary percussion drilling device.

Preferably, the common holder comprises a connector member for the outertube, a coaxially arranged inner connector member directed in the samedirection for the inner tube and an oppositely directed connector memberfor the hydraulically operated rotary percussion drilling device. Theinner connector member is connected to a nipple consisting of twoportions comprising a shock absorber member for absorbing impact forcesdirected via the inner connector to the inner tube, while the sameimpact forces in the direction toward the outer connector for the outerpercussion tube come into effect to the tube without dampening.

According to a preferred embodiment, the two portions of the nipple areprovided at the opposite faces with corresponding flanges between whichthe shock absorbing member is clamped into position. The two portions ofthe nipple are located in the bush-shaped housing of the common holder,said holder being in direct connection with the rotary percussiondrilling device. The shock absorber member can be constituted by ahydraulically or pneumatically operated shock absorber.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the assembly is shown in the accompanying drawings andthe method is explained with the help of these drawings.

FIG. 1 shows a purely diagrammatic vertically sectioned view of theassembly; and

FIG. 2 shows a vertically sectioned view of a holder in a larger scale,as compared to FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

According to the proposed method, a pre-drilling is performed with afirst device, i.e. with the down-the-hole hammer and, in the same courseof operation with the help of the same installation, simultaneously asecond device operatively connected to the first device is operated,whereby the first device is isolated in a impact-dampening manner fromthe drilling impacts and vibrations intended to take effect onto thesecond device. Thus, the mentioned influences are elastically cushioned,absorbed or at least dampened. Thus, the above mentioned drillingimpacts take effect practically exclusively onto the second device, i.e.the hydraulically operated percussion drilling device.

For the illustration, in a first approach, reference is made to FIG. 1in which there is shown a diagrammatic view of an assembly suitable forperforming the method.

A hydraulically operated percussion drilling device is designated withreference numeral 1. Such a device is known and is used in manydifferent ways in drilling assemblies.

Connected to the percussion drilling device is a holder 2 whichcomprises connections for an impact drilling assembly including an outerpercussion tube 3 with a drilling crown 4 as well as for an inner tube5. The inner tube 5 is equipped, at its end which has to be insertedinto the bore-hole, with a pneumatically or hydraulically operateddrilling hammer 6. The exact design of the holder 2 will be explainedherein below with reference to FIG. 2. The drilling hammer 6 is designedas a down-the-hole hammer having a chisel 7 which protrudes somewhat outof the percussion tube 3 which is surrounded by the inner tube 5, as canbe clearly seen in FIG. 1.

The connection of the inner tube 5 to the holder 2 is performed with thehelp of a shock absorbing member 8 which absorbs or, at least,considerably dampens the impacts and vibrations created by thepercussion drilling device 1 to such an extent that these influences nolonger have any effect on the inner tube 5 and, thereby, to the drillinghammer 6. On the other hand, the outer percussion tube 3 transforms theimpact forces to the drilling crown 4.

A pipe 9 for the supply of a pneumatic operating fluid leads from theoutside through the holder 2 and through the inner tube 5 to thedrilling hammer 6 to operate the latter one. The air escaping from thechisel 7 exclusively serves for flushing the drilled-out material out ofthe bore-hole which, thereafter, is led back through the annular chamber10 to the holder 2 and is finally removed.

In FIG. 2, the holder 2 is shown with its more important designcharacteristics and details in a larger scale. The holder 2 comprises atube-shaped housing 11 which is provided, at its one end, with a bushmember 12 protruding out of the housing and being provided with an innerthread 13 for the connection of the outer percussion tube 3. The otherend of the bush member comprises a flange 14 which is fixed to thefacing front surface of the housing 11 by means of screws 15. Twoapertures of the housing 11 are designated with reference numeral 16. Inthe interior of the housing 11, there is provided a two-part nipple,composed of a portion 17 and a portion 18 in coaxial relationship,whereby the first nipple portion 17 is screwed to a head portion 19which, itself, is screwed into the housing 11 at the open end thereof bymeans of its flange 20. The head portion 19 is provided with a connectorsleeve 27 for a percussion drilling assembly.

Between the two portions 17 and 18 of the nipple, there is clampinglyfixed a shock absorber member 21 (designated as element 8 in FIG. 1).This shock absorber member 21 can be constituted by a resilientmaterial, consisting of one or several layers. Important is that theshock absorber element 21 has exceptional shock absorbing properties topractically entirely destroys the impact forces and vibrations createdby a percussion drilling device.

In the place of an elastically resilient disc-shaped element, there maybe provided a hydraulically or pneumatically operating shock absorberelement which can be designed similar to a shock absorber used invehicles. If a suitable shock absorbing cylinder is used, very strongimpact forces can be dampened and absorbed. By adjusting the shockabsorbing effect, a simple adjustment of the assembly can be realizedwith regard to the present requirements.

The percussion drilling device designated with reference numeral 1 inFIG. 1, known per se in the art, is connected to the head portion 19whereby the created impact forces are transformed by means of the flange20 not only to the housing 11 but also to the flange of the nippleportion 17. The housing 11 is connected to the percussion tube 3 bymeans of the bush member 12, and the percussion tube 3 performs thedrilling operation under the influence of the impact forces with thehelp of the drilling crown 4.

The nipple portion 18 which is shock-isolated by the shock absorbermember 21 is fixed to a double sleeve 22 which comprises a connector 23for the inner tube 5. The latter one receives, at its remote end, thedrilling hammer 5 with the chisel 7. The drilling hammer 5 ispneumatically operated whereby pressurized air is fed through a suitablepipe (not shown), the pressurized air flowing through a connector 24 andfurther through apertures 25 and 26 into the nipple portion 17 and,thereafter, through a not shown central bore of the shock absorbermember through the nipple portion 18 into the inner tube 5.

In this manner, a very efficient working is made possible in which anexchange of the operating tools can be avoided. The proposed provisionof the shock absorber member has the effect that the impact forces ofthe hydraulically operated rotary percussion drilling device 1practically exclusively is directed to the outer tube 3 and that thedrilling hammer 6 in the interior of the tube 5 is not damaged.Furthermore, a loosening of the threaded connection of the inner tube 5is excluded since the vibrations of the hydraulically operated rotarypercussion drilling device 1 are absorbed by the shock absorber member21. A simultaneous operation of both devices is made possible, i.e. thebore-hole is drilled by means of the pneumatically operateddown-the-hole hammer and, in the same course of operation, the bore-holeis continuously and simultaneously increased in size by the operation ofthe percussion drilling device coupled with the down-the-hole hammer.

It is also possible to compose the outer percussion tube 3 and/or theinner tube 5 of several partial tube members by a threaded connectionwhereby the usual left-handed and right-handed threads can be used.Under all circumstances, even inner tubes of sectional design are sparedfrom impact forces and vibrations such that a loosening of the threadedconnections is not possible.

I claim:
 1. A drilling method for drilling a bore-hole in ground orsoil, with a percussion drilling device operated directly in thebore-hole and with a rotary percussion drilling device operated from thesurface of the ground or soil, both devices being received in a commonsupport member and adapted to be simultaneously operated, characterizedin that drilling impact forces and vibrations directed to said rotarypercussion drilling device from the surface are registered, elasticallydampened and absorbed prior to having an effect on said percussiondrilling device.
 2. A drilling assembly for drilling a bore-hole inground or soil, comprising:a first percussion drilling device operateddirectly in the bore-hole; a second rotary percussion drilling deviceoperated from the surface of the ground or soil; both said first andsecond devices being received in a common support member and adapted tobe simultaneously operated; said assembly comprising a drilling hammerwith a chisel member connected to an inner tube and an outer tube with adrilling crown surrounding said inner tube; said inner tube supportingsaid drilling hammer being connected, via a shock absorber element, tosaid common support member which is coupled with said rotary percussiondrilling device.
 3. The assembly according to claim 2 in which saidcommon support member comprises an outer connector member for said outertube, a coaxially arranged inner connector member directed in the samedirection for the inner tube and an oppositely directed connector memberfor said rotary percussion drilling device, whereby the inner connectormember is connected to a nipple consisting of two portions comprisingsaid shock absorber element for absorbing impact forces directed via theinner connector member to the inner tube, while the same impact forcesin the direction toward the outer connector member for the outer tubecome into effect to the tube without dampening.
 4. The assemblyaccording to claim 3 in which said two portions of the nipples areprovided at opposite faces with corresponding flanges between which theshock absorber element is clamped into position.
 5. The assemblyaccording to claim 4 in which said two portions of the nipple arelocated in a bush-shaped housing of the common support member, saidcommon support member being in direct connection with the rotarypercussion drilling device.